The present invention relates to a crawler-propelled truck movable on power-driven crawlers or endless chains of plates, and more particularly to a crawler-propelled truck equipped with a small-size power unit having its center of gravity located in a low position.
Some conventional crawler-propelled trucks have an engine for driving the crawlers, the engine being a horizontal engine with its crankshaft lying horizontally. In order to transmit engine power to the drive wheels engaging the crawlers, the crawler-propelled trucks include a power transmission mechanism such as a gear train or a belt-and-pulley mechanism between the crankshaft and the gear transmission or between the gear transmission and the drive wheels. Disadvantageously, such a drive unit including the engine, the gear transmission, and the power transmission mechanism is large in size, whereby a load-carrying space on the truck is correspondingly reduced. The large-size drive unit is also disadvantageous in that its center of gravity is necessarily relatively high.
Both front and rear wheel drive systems have been proposed for driving the crawlers of the crawler-propelled trucks. Those crawler-propelled trucks which are equipped with a crawler tensioning mechanism employ a front wheel drive system with the crawler tensioning mechanism associated with the rear wheels.
When the crawler-propelled truck with the front wheel drive system moves over an irregular road surface, however, shocks imposed by road surface irregularities on the front wheels are transmitted directly to the truck chassis. This has led to a problem in that the crawler-propelled truck cannot follow such an irregular road surface very closely or in a quick response.